Most vehicles dissipate kinetic energy during braking through friction brakes and engine compression braking, rather than capturing and storing the energy for reuse. It is widely recognized that this is a very wasteful use of energy, and recapture of the energy for accelerating the vehicle from is advantageous.
U.S. Pat. No. 6,279,550 to Bryant, which is herein incorporated by reference for all that it contains discloses a method of deriving mechanical work from a combustion gas in internal combustion engines and reciprocating internal combustion engines for carrying out the method. The invention includes methods an apparatuses for managing combustion charge densities, temperatures, pressures and turbulences in order to produce a true mastery within the power cylinder in order to increase fuel economy, power, and torque while minimizing polluting emissions.
U.S. Pat. No. 6,922,997 to Larsen, which is herein incorporated by reference for all that it contains discloses a motor vehicle kinetic energy recovery system that uses one or more cylinders of an internal combustion engine as the first or primary stage in a multi-stage high pressure air compression system, a compressed air storage system, compressed air operated drive train boosters and vehicle management electronics to provide cooperation between the air compression, storage and booster systems. The multi-stage, high pressure air compressor system is operable through engine compression braking allowing kinetic energy of a vehicle to be recaptured during retardation of vehicle speed.
U.S. Pat. No. 6,488,345 to Woody et al., which is herein incorporated by reference for all that it contains discloses a regenerative braking system and method for a batteriless fuel cell vehicle includes a fuel cell stack, a plurality of ancillary loads, and a regenerative braking device that is coupled to at least one wheel of the vehicle. The regenerative braking device powers ancillary loads when the vehicle is coasting or braking. The fuel cell powers the loads when the vehicle is accelerating or at constant velocity. The regenerative braking device dissipates power in an air supply compressor when the vehicle is traveling downhill to provide brake assistance. The compressor can be run at high airflow and high pressure to create an artificially high load. A bypass valve is modulated to adjust the artificially high load of the compressor. A back pressure valve protects the fuel cell stack from the high airflow and pressure. A controller controls a brake torque of the regenerative braking device as a function of vehicle speed and modulates the bypass valve.